title: The secretion apparatus of Pseudomonas aeruginosa: identification of a fifth pseudopilin, XcpX (GspK family).
abstract: The xcp gene products in Pseudomonas aeruginosa are required for the secretion of proteins across the outer membrane. Four of the Xcp proteins, XcpT, U, V and W, present sequence homology to the subunits of type IV pili at their N-termini, and they were therefore designated pseudopilins. In this study, we characterized the xcpX gene product, a bitopic cytoplasmic membrane protein. Remarkably, amino acid sequence comparisons also suggested that the XcpX protein resembles the pilins and pseudopilins at the N-terminus. We show that XcpX could be processed by the prepilin peptidase, PilD/XcpA, and that the highly conserved glycine residue preceding the hydrophobic segment could not be mutated without loss of the XcpX function. We, therefore, classified XcpX (GspK) as the fifth pseudopilin of the system.
authors.affiliation: Laboratoire d'Ingéniérie des Systèmes Macromoléculaires, UPR9027, IBSM/CNRS, Marseille, France.
authors.forename: S
authors.initials: S
authors.lastname: Bleves
authors.forename: R
authors.initials: R
authors.lastname: Voulhoux
authors.forename: G
authors.initials: G
authors.lastname: Michel
authors.forename: A
authors.initials: A
authors.lastname: Lazdunski
authors.forename: J
authors.initials: J
authors.lastname: Tommassen
authors.forename: A
authors.initials: A
authors.lastname: Filloux
mesh_terms: D000595:Amino Acid Sequence; D001345:Autoradiography; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D036781:Fimbriae Proteins; D015870:Gene Expression; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins; C111058:XcpX protein, Pseudomonas aeruginosa; D036781:Fimbriae Proteins